Anna and Ryan are the perfect couple. They have scientific proof. A few years ago, the pair took part in a new test. They each tore off a fingernail and put it in a machine that judges their relationship. Anna and Ryan scored a perfect 100%.¹

Yet Anna is restless. Her life with Ryan has become stale. Maybe her own relationship is not so perfect after all?

This is the plot of Fingernails, a new film by Greek director Christos Nikou. It has a fascinating central concept. What if we had a machine that could tell us if we were truly in love?

This may not be so far away. Dating apps already assess how compatible people are based on their user history and conversations. But the Fingernails machine would be a huge advance.

It could stop others from staying in the wrong relationships. There are thousands of divorces and break-ups each year.² The machine could prevent unsuitable couples from marrying in the first place.

It could also help people come to terms with unrequited love. If someone is in love with you but the feeling is not returned, take the test with them to clear the air. In Thomas HardyAn English novelist and poet.'s Far From the Madding Crowd, William Boldwood falls dangerously in love.³ Machine-generated proof might help him move on.

Yet there are downsides to being informed. Love is not always at first sight. People change. Feelings develop. When Elizabeth Bennet meets Mr. Darcy in Jane AustenAn English novelist most famous for writing Pride and Prejudice.'s Pride and Prejudice, they form an instant dislike. They would have scored 0%. But by the novel's end, they realise they are a perfect match.

Love is stranger and more complex than a number. As Author Marian Keyes writes: "Love is an emotion. It can't be seen or touched, and it is experienced differently by everyone, therefore it is difficult to measure."

Yes: The fingernail machine is just the start. Imagine if we had devices that could detect all our emotions and help us manage them. Machines can improve our lives by teaching us more about ourselves.

No: The machine is the start of a slippery slope. What if we began assigning ratings to people's personalities and abilities? It might lead to a world where our lives are controlled by numbers.

Or... Love is not a number. It is not a constant state but a voyage, changing over time, mixing the good and the bad. This is its beauty. A machine-generated score misses the point completely.